[RFC] Variable syntax tweaks

Hi internals, I'd like to propose a small RFC, which addresses a few minor issues that have not been handled by the original "uniform variable syntax" RFC: https://wiki.php.net/rfc/variable_syntax_tweaks This is all about edge cases of edge cases, of course. I think the only part here that is not entirely straightforward and may need some discussion is how arbitrary expression support for instanceof should be handled. Regards, Nikita